1. Field of the Invention
The present invention relates to an I/O card device, and particularly to an I/O card device having a secure engagement structure between metallic covers and insulative frames thereof for ensuring that the frames will not become disengaged from the covers even after extended use of the I/O card device, whereby connectors fitted with the frames can be securely fixed in position for ensuring a stable electrical signal transmission between the device and a computer incorporating the device.
2. The Prior Art
An I/O card device is inserted into a card connector of a computer for expanding functions of the computer. Conventionally, the I/O card device consists of an upper and a lower metallic cover, an upper and a lower dielectric frame, a printed circuit board (PCB) and two connectors. The frames are mounted to the upper and lower covers by clamping engaging tabs formed by the covers onto the frames. The connectors which have been soldered to the PCB are mounted to the device by fitting mounting ears thereof into the frames. Such prior art is disclosed in U.S. Pat. Nos. 5,242,310, 5,339,222, and 5,397,857.
The covers and the frames of the conventional I/O card devices do not have a secure connection therebetween, therefore after extended use of the card device, the frames may disengage from the covers thereby causing the connectors to move relative to the covers which adversely affects the signal transmission between the computer and the I/O card device.
To overcome the above disadvantage, U.S. Pat. No. 5,502,892 proposes to injection mold the frames directly to the covers. Although this method improves the connection between the covers and the frames, the injection molding process does not enhance the mechanical engagement between the frames and the covers, which still causes the frames to disengage from the covers after extended use of the I/O card device.
Hence, an improved I/O card device is needed to eliminate the above mentioned defects of current I/O card devices.